Inspection Procedure 1: When the ignition switch is turned to the "ON"
position (engine stopped), the brake warning lamp does not
illuminate.
OPERATION
- The brake warning lamp is lit up by transistor control in the ASTC-ECU.
However, the relationship of the reverse circuit movement in the combination
meter will vary from usual in terms of transistor ON/OFF and brake
warning lamp ON/OFF, in that the brake warning lamp will lamp up when
the transistor is turned OFF for this circuit. This is how the brake warning
lamp lights up even when the ASTC-ECU connector is connected improperly or
if the ASTC-ECU function has terminated.
- The ASTC-ECU also lights up the brake warning lamp during the initial
check (approximately 3 seconds) when the ignition switch is turned to the
"ON" position in addition to when the system is malfunctioning.
COMMENT ON TROUBLE SYMPTOM
Possible causes include the combination
meter power circuit, disconnected earth circuit, dead lamp bulb, or short
circuited brake warning lamp.
PROBABLE CAUSES
The most likely causes for this case
are:
- Blown fuse
- Damaged wiring harness or connector
- Burnt out brake warning lamp bulb
- Combination meter defect
- Malfunction of the ASTC-ECU
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STEP 1. Voltage measurement at combination meter connector
D-02.
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(1)Do not disconnect combination meter connector D-02, and
check at the harness side.
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(2)Turn the ignition switch to the "ON" position.
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(3)Measure the voltage between terminal 45 and
earth.
OK: System voltage
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Q.
Is the check result normal?
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 Go to Step 2.
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 Replace the combination meter.
Then go to Step 5.
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STEP 2. Connector check: D-02 combination meter connector, D-223
ASTC-ECU connector and D-230 intermediate connector.
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Q.
Is the check result normal?
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Go to Step 3.
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Repair the defective connector.
Then go to Step 5.
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STEP 3. Check the harness wire between the combination meter connector
D-02 terminal 45 and ASTC-ECU connector D-223 terminal 81.
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the harness wire. Then go
to Step 5.
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STEP 4. Retest the system.
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Q.
Does the brake warning lamp illuminate for 3 seconds when the ignition
switch is turned to the "ON" position with engine stopped or upon
start-up?
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It can
be assumed that this malfunction is intermittent. Refer to GROUP 00, How to
Use Troubleshooting/Inspection Service Points - How to Cope
with Intermittent Malfunction  .
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Repair the ASTC-ECU. Then go to
Step 5.
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STEP 5. Retest the system.
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Q.
Does the brake warning lamp illuminate for 3 seconds when the ignition
switch is turned to the "ON" position with engine stopped or upon
start-up?
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The
procedure is complete.
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Start over at Step 1.
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